Improvement in oscillating printer bar for recorders



May 11, 1954 R BEAM 2,678,255

IMPROVEMENT IN OSCILLATING PRINTER BAR FOR RECORDERS Filed Dec. 10, 1948 2 Sheets-Sheet l INVENTOR. RICHARD L. BEAM ATTORNEY R. L. BEAM May 11, 1954 IMPROVEMENT IN OSCILLATING PRINTER BAR FOR RECORDERS 2 Sheets-Sheet 2 Filed Dec.

x-CURVE 1 INVENTOR. RICHARD L. BEAM Wad/4m HTTOR/VEY Patented May 11, 1954 IMPROVEMENT IN OSCILLATING PRINTER BAR FOR RECORDERS Richard L..Beam, Great Neck, N. Y., assignor to Faximile, Inc., New York, N. Y., a corporation of Delaware ApplicationDecember 10, 1948, Serial No. 64,505

9 Claims. (Cl. 346-101) '1 "The present invention concerns facsimile'recorders and, in particular, facsimile recorders oi the type employing helical and linearelectrodes for recording on a record sheet.

The term'facsimile is generally applied to the process which includes thesteps of scanning a subject copy ofgraphic material, usually with a small spot of light, generating electrical signals representing density variations point by point of the subject copy, conveying these electrical signals to a distant point,.and reproducing them as density changes on a'record sheet to represent exactly the original'copy. A recording point is utilized'at the receiving end to scan the record sheet in synchronism with the scanning point of lightwhichis utilized to cover the original copy. One well known method of producing the density variations in the record sheet is-to pass the electrical current through an electrolytically sensitive'sheet so as to produce acolor change, which is a'func'tion of the instantaneous recording current. One type of recorder which is well suited to this'purpose includes a rotatable drum carrying a helical electrode. The drum is driven by a motor in synchronism with the transmitter scanner and the helical electrode intersects a linear electrode, usually considered the stationary electrode, while the record sheet is drawn at a steadyrate between the two electrodes. Some of the recording processes, such as-the one in which a color-lake is formed upon the recording sheet, involve consumption of the linear electrode. For this type of'recording the linear electrode is usually in theform of a thin steel blade. In order to provideaccuraterecording, the intersecting edge of this blade must be straightand clean and free from dips or unevenness. Since the recording process involves consumption of this blade it has been found that; ifJa stationary blade is used, uneven wear results, particularly where long vertical linesv are reproduced upon the recording sheet, causing the blade edgeto have a corrugated appearance and preventing high fidelity recording.

'Ithas been found that, if the linear electrode is'moved back and forth along its length, the wear and consumption of the electrode may be distributed, keeping the edge accurately straight and usable for a much longer period of time than if it is allowed to remain stationary. In the copending application of John H. Long entitled Facsimile Printer Blade, filed on October 15, 1946, and bearing'the Patent No. 2,505,779, there is described a printer blade which is moved back and forth along its length in order to distribute the wear of the blade. The motion of the blade in this case is essentially sinusoidal wherein the velocity of motion varies considerably over its path of travel, having points of high velocity and others of zero velocity. While this is a great improvement over the use of a stationary blade, it has been found, according to the present invention, that if the motion is modified so that the velocity is essentially constant as the blade moves back and forth, there is a still furtherimprovement and increase in the life of the blade. The sinusoidal motion does not permit the blade to be consumed equally at all points throughout its usabie length. 'An oscillatory motion that produces essentially constant velocity throughout the complete oscillatory cycle is needed to overcome this eiiect.

The present invention is concerned with a method and means of obtaining constant velocity over the complete motion cycle of the printer blade. An analysis ofthe problem leads to the conclusion that the answer required is one of mechanically producing a triangular wave pattern wherein therate of motion in one direction is of constant velocity, the rate of motion in the return direction is also of constant and equal velocity, and the reversal of motion at either end of the oscillating span is instantaneous. It is well knownin the art that a fundamental fre quency plus certain of its harmonics, in proper amplitude relationship as determined by a Fourier Series Analysis of the desired wave form, can be superimposed on one another to produce the wave shape wanted. Thus, where a triangular wave shape is required, it can be demonstrated that'a fundamental frequency plus a third har monic of that frequency having one-ninth the amplitude of the fundamental, and plus other suitably selected harmonics having proper amplitudes, may be algebraically added to produce a triangular wave. The relationshp of the harmonies to the fundamental, in both frequency and amplitude, may be calculated by using equations obtainable in any advanced mathematical or physics textbook. One such source is, Waveform Analysis, by R. G. Manley, published by John Wiley & Sons, Inc. Having theoretically det roamed the fundamental and harmonic waves required, there is then needed mechanical means for producing such waves, adding them algebraically and of using the resultant wave motion to oscillate the printer blade. This invention is concerned with obtaining the theoretical analysis and of mechanically producing the triangular wave motion described.

Accordingly, it is one object of the present invention to provide a moving printer blade in a facsimile recorder embodying helical and linear electrodes in which the velocity of motion is substantially constant throughout the path of travel of the blade.

Another object of the invention is to provide simple and efficient means for obtaining substantially equal velocity and constant motion in a moving printer blade for a facsimile recorder.

These and other objects of the present invention will be apparent from the detailed description given in connection with the various figures of the drawings.

In the drawings:

Fig. 1 shows the essential components of a facsimile recorder embodying one form of the present invention.

Fig. 2 shows an enlarged view of a portion of the form of the invention shown in Fig. 1.

Fig. 3 shows various curves useful in explaining the operation of the present invention as shown in Figs. 1 and Fig. 1 shows the essential components of a facsimile recorder in which a rotatable drum I carrying a helical electrode 2 mounted on a shaft 3 is rotated by a suitable motor 4 receiving power over leads 5 and 6. Recording is accomplished upon a recording sheet I by the cooperation of helical electrode 2 and a linear electrode or printer blade 8 carried by a frame 9. Recording sheet I is drawn through the recorder by suitable means such as cooperating rollers I and I I which are driven in some suitable manner not shown. A gear I2, being a transfer means, is rotated by the driving means of shaft 25 extending from roller I0 and this gear in turn meshes with a second gear I3. Gear I3 is mounted on arm I4 and is in floating relationship to gear I2. Arm I4 is pivoted at point 21, activated by means of the motion of pin 26. The motion of arm I4 is imparted to a second arm I which is spring loaded to pull it in one direction by means of spring I6. By means of the motion of arm I4 and the return pull of spring I6, arm I5 is moved up and down and pulls wire I! against the action of spring 22. Wire I'I passes over pulleys I9 and mounted on frame It to a fastening 24 in cross arm 21 thereby imparting sliding motion to arm 2I. frame 9 and hence its motion is transmitted to blade 8 causing it to move back and forth across the recording sheet I. The pull of wire II moves arm 2| and hence blade 8 in one direction and return spring 22, fastened to frame 23, pulls it back to its original position. In order to impart the desired type of velocity motion to the printer blade 8, both gears I2 and I3 are eccentric. Shaft 25 is displaced "from the center of gear I2 and pin 26 is displaced from the center of gear I3.

Fig. 2 shows gears I2 and I3 in more detail and illustrates their eccentricity. One arrangement of providing the linear velocity motion of printer blade 8 is illustrated, wherein the ratio of gear I2 to gear I3 is 3 to 1 and the eccentricity of gear I2 is nine times the eccentricity of gear I3. The relative gear sizes result in a fundamental wave in the large gear I2 linkage, with the third harmonic of the fundamental being produced in the small gear I3. The eccentricity ratio of nine in gear I2 to one in gear I3 makes the amplitude of the third harmonic produced by gear I2, one-ninth of the fundamental produced by gear I2. Gears I2 and I3 are placed in mesh so that once during the revolution of gear I2 its Arm 2I is fastened to I iii) point of maximum positive amplitude corresponds to the maximum positive amplitude point of gear I3 and its point of maximum negative amplitude corresponds to the maximum negative amplitude of gear I3. During one revolution of gear I2, gear I3 goes through three positive maximum and three negative maximum points. are the maximum positive amplitudes and maximum negative amplitudes of a third harmonic wave. Thus, by the system presented, gear I2 and gear I3 combine to give a wave signal that is the algebraic sum of a fundamental and a third harmonic having an amplitude that is oneninth that of the fundamental.

Fig. 3 shows how the velocity components contributed by the eccentric gears can be added to give a substantially linear velocity curve with a substantially instantaneous reversal of motion at each end of the travel of the linear electrode. Curve I shows the velocity components contributed by a gear contributing the fundamental motion, curve 2 shows a velocity component contributed by a second gear in proper harmonic relation to the first gear. Curve 3 is the ultimate sum of curves I and 2 and others of proper characteristics, showing the actual velocity versus time distribution of motion for a linear electrode driven by a gear system developed along the lines of the type shown in Figs. 1 and 2, but having more than two eccentric gears. As shown in curve 3 the velocity of travel of the linear electrode is substantially constant with a reversal at time T2. The slope of curve 3 represents the velocity of travel of the linear electrode while its vertical component represents amplitude of motion. It will be seen, therefore, that the linear electrode moves at a substantially uniform rate of speed from the initial position at time TI to a maximum positive displacement at time T2 whereupon it immediately reverses its direction of travel and returns to its initial position at a substantially uniform rate of speed, arriving there at time T3. Time TI to time T3 represents one complete traverse of the linear electrode corresponding to one revolution of the larger driving eccentric gear I2, or of one full cycle of the fundamental frequency chosen.

Triangular path or curve 3 represents the ultimate path of motion of the oscillating blade, if all of the proper harmonic frequencies were used in their proper proportion to the fundamental. It is evident that adding all of the proper harmonic frequencies will ultimately produce the slope and amplitude of the curve herein described. Usually, the use of greater than the third harmonic is unwarranted in view of the mechanical complications involved. Because of this fact the solution presented in Figs. 1 and 2 is considered to be the most practical. Nevertheless, if a more accurate curve is desired, more gears, representing the additional harmonics in proper frequency and amplitude relationship, may be used.

While only a single embodiment of the present invention has been shown and described many modifications will be apparent to those skilled in the art within the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a recorder, the combination of, a rotatable helical electrode, a linear electrode for coopcrating with said helical electrode to record upon a recording sheet, means for moving said linear electrode back and forth along its length, and means for actuating said moving means at sub- These points stantia-lly constant velocity between points of reversal of direction of movement.

2. In a recorder, the combination of, a rotatable helical electrode, a linear electrode for cooperating with said helical electrode to record upon a recording sheet, and means for moving said linear electrode in the direction of its length with a motion which is the sum of a simple harmonic motion and the third harmonic thereof to provide substantially constant velocity displacement of said linear electrode back and forth between two extremesof motion.

3. The combination as set forth in claim 2 wherein the electrode moving means includes the combination of a driving means, a power transfer means eccentrically coupled to said driving means and a floating power transfer means having eccentric motion, cooperating with said first transfer means.

4. The combination as set forth in claim 2 wherein the electrode moving means includes at least two cooperating eccentric power transfer means having different diameters and eccentricities and power means for driving one of said power transfer means.

5. The combination as set forth in claim 2 wherein the electrode moving means includes at least two meshing eccentric gears of different pitch diameters and eccentricities and driving means for one of said gears.

6. The combination as set forth in claim 2 wherein the electrode moving means includes the combination of, a driving means, a gear eccentrically mounted on a shaft attached to said driving means, a second gear eccentrically mounted on a second shaft and meshed with first said gear, said gears having a gear ratio of substantially three to one and an eccentricity ratio of substantially nine to one, said second shaft being free to move in a line at right angles to the plane of said gear axis, and a linkage coupled to said second shaft to utilize the substantially constant velocity motion of said shaft to move said linear electrode.

'7. In an electrolytic recording device, the combination of, a rotatable helical electrode, a linear electrode for cooperating with said helical electrode to record upon a record sheet, and at least two eccentric gears of difierent pitch diameters coupled to said linear electrode for moving said linear electrode back and forth along its length.

8. The combination as set forth in claim 1 wherein said moving means includes at least two eccentric gears.

9. The combination as set forth in claim 1 wherein said moving means includes at least two eccentric gears having different pitch diameters and eccentricities.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,131,547 Artzt Sept. 23, 1938 2,187,758 Seybold Jan. 23, 1940 2,285,534 Ryan June 9, 1942 2,397,535 Cooley Apr. 2, 1946 2,505,779 Long May 2, 1950 

